The present invention relates to a control system for a sprinkler system and, more particularly, to a control system for a preaction sprinkler system.
There are several types of preaction systems, but all preaction systems typically employ closed sprinklers in the sprinkler system piping. The detection system may be hydraulic, pneumatic, or electric and may be actuated manually or by detecting a temperature rise or by other means. Typically, the detection system operates before the sprinkler fuses and sounds an alarm. Preaction systems are used in areas where it is desirable to keep water intrusion to a minimum, such as areas that are subject to high potential water damage or freezing of the system piping.
Current technology requires continuous power to the various components that control the opening and closing of the flow control valve. For example, in the trim piping for some preaction systems, a normally open solenoid valve is used to control the pressure in the priming chamber of the system control valve. The solenoid valve must be powered closed during normal system operation. When a fire occurs, the solenoid valve is de-energized and opens to release the main sprinkler system control valve. However, this requires back-up power and a continuous power condition for the solenoid valve, which may result in a high-heat condition and possible failure due to sticking and/or failure of the electrical coil of the solenoid valve. In order to make these systems fail-safe, the system relies on a loss of power condition to release the main valve to allow the system to operate.
Consequently, there is a need for a preaction system that can fail-safe but which can operate in a no-power condition.